Pulverulent preparation of phosphoric



LI'OSS HGTEFBHCB PATENT OFFICE.

EBEN n. nonsroni), or CAM RIDGE, MASSACHUSETTS.

PULVERULENT PREPARATlON OF PHOSPHORIC SPECIFICATION forming part ofLetters Patent No. 229,705, dated July 6, 1880.

Application filed May 14, 1:380. (No specimens.)

2,979, dated June 9, 1.868, there was described ,or less acid reaction,whether wholly united,

a pulverulent preparation of phosphoric acid having the characteristicsand capable of the uses therein specified. The phosphoric acid of myformer preparations was, however, invariably combined with lime in suchproportions-as to form phosphates possessing-more to the base, so as toconstitute therewith a 4 strictly chemical salt, or only partially so.

By as much, therefore, as this combinationwith a base neutralized theacidity of the phosphoric acid, by so much were its strength andeificiency diminished for the purposes, of em ployment with alkalinecarbonates in breadmaking or in other processes requiring the liberationof carbonic acid gas. But until my discovery and invention, herein to bedisclosed, I had not known or supposed that phosphoric acid uncombinedwitha base or dissociated from acid phosphates'formed therewith could bereduced to a' pulverulent condition by admixture with aneutralsuhsta-ncelike starch and keptinert,to heiitiliied aftor thehianner ofmyformer preparations, This 'discovery' and the invention which Ihavemade it practicallyavailable enable me to preserve the .fullst rength.of the phosphoric acid for the purposes of reaction upon alkalinecarbonates without'the waste and expense attending itspartial'neutralization 1,359 base.

My present invention may be efliciently practiced by the following modeof procedure: I take acid -phosphate liquor, substantially such as is.prepared by the process described in my patent of April 22, 1856, andstanding,

for example, at 15 Baum, or the same may be otherwise-produced byadding, with constant a itatio'n' of thediquid, one thousand six h'unred poundsjof pulverized bone-black ate of soda to to a diluted solutionof one thousand one hundred pounds of oil of vitriol, (one of oil ofvitriol to three of water), and when the decomposition is complete,which [(fqllllQS some eighteen in combination with phosphoric acid,thereby producing gypsum and setting frce phosphoric acid. The emulsionis allowed to cool and the gypsum is separated by filtration. Theliltrate is then further concentrated in porcelain to about one-fourthof the original volume. To

this, after cooling, I add, in successive portions, with stirring forthorough incorporation, a weight of starch inversely proportioned to theintended acid strength of the product.'

Thus, if. I desire that twenty parts of the pulverulent acid sliallneutralize nine pa 1- 9f bicarbonate of soda, I add, for every onethousand cuhic centimeters of the original liquid of 15 Baum threehundred and sixty grams of starch. I incorporate these constituents in-.

timately, spread the mass out to dry in a warm room,- and, when dry,pulverize'it. I

' In reducing the acid phosphate liquor of my former patent,hereinbet'ore specified, to a pulverulent condition, as therein setforth, the quantity of starch equired was as about one hundred grams 'toevery one thousand cubicz centimeters of the liquor taken at 15 Baum.

It will therefore be seen that in order to accomplish the resultsattained by my present invention a very much greater relative propor-'tion of the neutral-substance is needed.

The pulverulent phosphoric acid so produced I have found by'quantitativetest to have the same strength that the liquid alone possessed afterseparation of the gypsum. .[t may be thoroughly mixed with dry bicarboirform a baking or elibrvescing powder, which Willkeep in bottles or vanswithout reaction, and will, when mixed with water, yield carbonic acidgas for the purposes desired. I i

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The gypsum formed by the introduction of the sulphuric acid into theacid phosphate'liqnor does not impair the acid strength of the product,if permitted, without being filtered off, to remain as a part of it; butits elimination is preferable, especially for pharmaceutical purposes.

I am aware that M. Bianc'lugifd, of Puteaux, France, has described aprocess of separating lime from acid phosphate liquor by adding; an

equivalent of sulphuric acid, evaporating the liquor, and separating thegypsum produced by decantation of the supernatant liquor; but this doesnot constitute my invention.

I claim as my invention- 1. The process of producing pulverulentphosphoric acid by treating the acid liquid described herein so as tobring it to the condition of free phosphoric acid, and combining thesame with starch in about the proportions 20 stated, drying, andpulverizing'.

2. A pulverulent preparation ot'phosphoric acid substantially free fromcombination or association with any base, and kept in the state of drypowder by admixture only with a neutral. substance like starch I 4 3. Abaking or efierveseing powder consist ing of the admixture ofpulverulent phosphoric acid, substantially such as described, with a dryalkaline carbonate. Cambridge, May 13, 1880..

E. N. HORSFORD.

Witnesses:

H. S. EUsTIs, GEO. A. BARTLETT.

